EP1891181B1 - Liquid-crystalline medium and liquid crystal display with 1,2-difluoroethene compounds - Google Patents

Abstract

Liquid crystalline medium (A) with positive dielectric anisotropy based on a mixture of compounds, comprises one or more 1,2-difluoroethene compound (I). Liquid crystalline medium (A) with positive dielectric anisotropy based on a mixture of compounds, comprises one or more 1,2-difluoroethene compound of formula (I). R 1> : halogenated or unsubstituted 1-15C alkyl- or alkoxy residue (where one or more CH 2-group is replaced by -Ctriple boundC-, -CH=CH-, -O-, -CO-O- or -O-CO-, and O atoms are not connected directly together); A 1> : -cyclohexane-, 4 heterocyclic compound e.g. -dioxane- or -pyrimidine-, -fluoro-benzene-, -1,3-difluoro-benzene-, -phenyl- or bicyclic compound of formula (a); Z 1>, Z 2> : a single bond, -Ctriple boundC-, -CF=CF- (preferred), -CH=CH-, -CF 2O- or -CH 2CH 2-; X : F, Cl, CN, SF 5 or halogenated or unsubstituted 1-15C alkyl- or alkoxy (where one or more CH 2-group is replaced by -Ctriple boundC-, -CH=CH-, -O-, -CO-O- or -O-CO-, and the O atoms are not connected directly together); L 1>-L 6> : H or F; and m : 0-1. Independent claims are included for: (1) an electro optical liquid crystal display comprising (A); and (2) a difluoroethene compound of formula (Ia). m : 1-2. [Image] [Image].

Description

The present invention relates to a liquid-crystalline medium containing 1,2-difluoroethene compounds, and to its use for electro-optical purposes and displays containing this medium. New 1,2-difluoroethene compounds of the invention are disclosed.

Liquid crystals are mainly used as dielectrics in display devices, since the optical properties of such substances can be influenced by an applied voltage. Electro-optical devices based on liquid crystals are well known to the person skilled in the art and can be based on various effects. Such devices include, for example, dynamic scattering cells, DAP cells (upright phase deformation), guest / host cells, twisted nematic (TN) cells, super-twisted nematic (STN) cells, SBE cells ("superbirefringence effect") and OMI cells ("optical mode interference"). The most common display devices are based on the Schadt-Helfrich effect and have a twisted nematic structure. In addition, there are also cells that work with an electric field parallel to the substrate and liquid crystal plane, such as the IPS cells ("in-plane switching"). Above all, the TN, STN and IPS cells are currently commercially interesting fields of use for the media according to the invention.

The liquid crystal materials must have good chemical and thermal stability and good stability against electric fields and electromagnetic radiation. Further, the liquid crystal materials should have a low viscosity and give short response times, low threshold voltages and high contrast in the cells.

Furthermore, they should have a suitable mesophase at usual operating temperatures, ie in the widest possible range below and above room temperature, for example, for the above-mentioned cells a nematic or cholesteric mesophase. Because liquid crystals usually used as mixtures of several components, it is important that the components are readily miscible with each other. Other properties, such as electrical conductivity, dielectric anisotropy and optical anisotropy, must meet different requirements depending on the type of cell and the field of application. For example, materials for cells of twisted nematic structure should have positive dielectric anisotropy and low electrical conductivity.

For example, for matrix liquid crystal displays with integrated non-linear elements for single pixel switching (MFK displays), media with high positive dielectric anisotropy, broad nematic phases, relatively low birefringence, very high resistivity, good UV and temperature stability, and lower vapor pressure are desired ,

1. 1. MOS (Metal Oxide Semiconductor) oder andere Dioden auf Silizium-Wafer als Substrat.
2. 2. Dünnfilm-Transistoren (TFT) auf einer Glasplatte als Substrat.

Such matrix liquid crystal displays are known. As non-linear elements for individual switching of the individual pixels, for example, active elements (ie transistors) can be used. One speaks then of an "active matrix", whereby one can distinguish two types:

1. 1. MOS (Metal Oxide Semiconductor) or other diodes on silicon wafer as a substrate.
2. 2. Thin-film transistors (TFT) on a glass plate as a substrate.

The use of monocrystalline silicon as a substrate material limits the display size, since the modular composition of various partial displays on the joints leads to problems.

In the more promising type 2, which is preferred, the TN effect is usually used as the electro-optical effect. A distinction is made between two technologies: TFTs made of compound semiconductors such as CdSe or TFTs based on polycrystalline or amorphous silicon. The latter technology is being worked on worldwide with great intensity.

The TFT matrix is applied on the inside of one glass plate of the display, while the other glass plate on the inside carries the transparent counter electrode. Compared to the size of the pixel electrode, the TFT is very small and practically does not disturb the image. This technology can also be extended to fully color-capable image representations, wherein a mosaic of red, green and blue filters is arranged such that each one filter element is opposite to a switchable image element.

The TFT displays usually operate as TN cells with crossed polarizers in transmission and are backlit.

The term MFK displays here includes any matrix display with integrated nonlinear elements, i. in addition to the active matrix also displays with passive elements such as varistors or diodes (MIM = metal-insulator-metal).

Such MFK displays are particularly suitable for TV applications (eg pocket TV) or for high-information displays for computer applications (laptop) and in the automotive or aircraft. In addition to problems with regard to the angle dependence of the contrast and the switching times, difficulties arise with MFK displays due to the insufficiently high specific resistance of the liquid-crystal mixtures [ TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, p. 141 ff , Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Liquid Crystal Displays, p. 145 ff , Paris]. With decreasing resistance, the contrast of a MFK display deteriorates and the problem of "after image elimination" may occur. Since the resistivity of the liquid crystal mixture decreases by interaction with the internal surfaces of the display, generally over the lifetime of an MFK display, high (initial) resistance is very important in order to obtain acceptable service lives.

In particular, in low-volt mixtures, it has not been possible to realize very high resistivities. Furthermore, it is important that the resistivity shows the smallest possible increase with increasing temperature and after temperature and / or UV exposure. Also particularly disadvantageous are the low-temperature properties of the mixtures of the prior art. It is required that no crystallization and / or smectic phases occur even at low temperatures, and that the temperature dependence of the viscosity is as low as possible. The MFK displays from the prior art thus do not meet today's requirements.

In addition to liquid crystal displays which use backlighting, ie are operated transmissively and optionally transflectively, reflective liquid crystal displays are also of particular interest. These reflective liquid crystal displays use the ambient light for information presentation. Thus, they consume significantly less energy than backlit liquid crystal displays of appropriate size and resolution. Since the TN effect is characterized by a very good contrast, such reflective displays are still easy to read even in bright ambient conditions. This is already from simple reflective TN displays as they are in z. As watches and calculators are used known. However, the principle is also on high-quality, higher-resolution active matrix driven displays such. B. TFT displays applicable. Here, as with the general conventional transmissive TFT-TN displays, the use of liquid crystals with low birefringence (Δn) is necessary to achieve a small optical retardation (d · Δn). This small optical delay leads to a mostly acceptable low viewing angle dependence of the contrast (cf. DE 30 22 818 ). For reflective displays, the use of liquid crystals with low birefringence is even more important than for transmissive displays, because with reflective displays the effective layer thickness through which the light passes is approximately twice that of transmissive displays with the same layer thickness.

There is thus still a great need for MFK displays with very high resistivity and large at the same time Operating temperature range, short switching times even at low temperatures and low threshold voltage, which do not or only to a lesser extent show these disadvantages.

• erweiterter nematischer Phasenbereich (insbesondere zu tiefen Temperaturen)
• lagerstabil, auch bei extrem tiefen Temperaturen
• Schaltbarkeit bei extrem tiefen Temperaturen (out-door-use, Automobil, Avionik)
• erhöhte Beständigkeit gegenüber UV-Strahlung (längere Lebensdauer)

In TN (Schadt-Helfrich) cells, media are desired which allow the following advantages in the cells:

• extended nematic phase range (especially at low temperatures)
• stable on storage, even at extremely low temperatures
• Switchability at extremely low temperatures (out-door-use, automotive, avionics)
• increased resistance to UV radiation (longer life)

With the media available from the prior art, it is not possible to realize these advantages while maintaining the other parameters.

In the case of higher-twisted cells (STN), media are desired which enable higher multiplexability and / or lower threshold voltage and / or broader nematic phase ranges (in particular at low temperatures). For this purpose, a further expansion of the available parameter space (clearing point, transition smectic-nematic or melting point, viscosity, dielectric values, elastic sizes) is urgently desired.

The invention has for its object to provide media especially for such MFK, TN or STN displays that have the disadvantages mentioned above not or only to a lesser extent, and preferably at the same time very high resistivities and low threshold voltages.

It has now been found that this object can be achieved if used in ads according to the invention media. The media according to the invention are distinguished by very low rotational viscosities γ ₁ in combination with a high clearing point (T _Cip ) and good low-temperature properties.

In the JP 06329566 A and in the US 5380461 A there are described fluorinated stilbenes which are partially related to the components of the mixtures of the present invention. Synthesis methods for this class of compounds are disclosed there.

The following references all refer to the cited derivatives as liquid crystal components:

The publication US 2001/0004108 A1 discloses difluorstilbene derivatives having 2 and 3 ring groups as part of a liquid crystal mixture of tolans and phenylcyclohexanes. The publication JP 03-294386 A discloses trans -dihalo-stilbene derivatives with polar end groups. The publication JP 06-329566 A discloses Difluorstilbene with two ring groups with other fluorine substituents. The publication EP 0560382 A1 discloses difluoroethylene derivatives having an adjacent cyclohexane ring. The publication DE 10155073 A1 discloses nonpolar difluorosthene levels and other mixture components, but not compounds with a -CF ₂ O- group. The publication EP 1215270 A1 discloses liquid crystal mixtures with difluorosthenbenes for passive displays. The publication DE 10151491 A1 discloses a generic group of compounds comprising difluorstilbene having an end group of the formula -SF ₅ . The publication DE 10124480 A1 discloses a generic formula comprising an optional -CF = CF group between rings and a final binding group of formula -SF ₅ . The publication WO 2004/106460 A1 discloses a generic 4-membered formula comprising an optional -CF = CF- group between benzene rings and a tetrahydropyran ring. The publication EP 1416030 A1 discloses an optional co-component (IV) of a liquid-crystal mixture which optionally represents a difluorostyrene.

The publication DE 102004008638 A1 discloses liquid crystalline mixtures with compounds comprising a -CF ₂ O- group.

enthält,
worin

R¹

einen halogenierten oder unsubstituierten Alkyl- oder Alkoxyrest mit 1 bis 15 C-Atomen, wobei in diesen Resten auch eine oder mehrere CH₂-Gruppen jeweils unabhängig voneinander durch -C≡C-, -CH=CH-, -O-, -CO-O- oder -O-CO- so ersetzt sein können, dass O-Atome nicht direkt miteinander verknüpft sind,

Ring A

ein nach links oder rechts ausgerichtetes Ringsystem der Formeln

Z¹, Z²

eine Einfachbindung, -C≡C-, -CF=CF-, -CH=CH-, -CF₂O-, oder -CH₂CH₂-, wobei mindestens eine Gruppe aus Z¹ und Z² die Gruppe -CF=CF- bedeutet,

X

F, Cl, CN, SF₅ oder einen halogenierten oder unsubstituierten Alkyl- oder Alkoxyrest mit 1 bis 15 C-Atomen, wobei in diesen Resten auch eine oder mehrere CH₂-Gruppen jeweils unabhängig voneinander durch -C≡C-, -CH=CH-, -O-, -CO-O- oder -O-CO- so ersetzt sein können, dass O-Atome nicht direkt miteinander verknüpft sind, und

L¹, L², L³, L⁴, L⁵ und L⁶

jeweils unabhängig voneinander H oder F, und

m

0 oder 1,

bedeuten,
und zusätzlich eine oder mehrere ausgewählte Verbindungen der allgemeinen Formeln K-1 bis K-12:

worin

R⁰

n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C- Atomen

bedeutet.The invention relates to a liquid-crystalline medium having a positive dielectric anisotropy based on a mixture of compounds, characterized in that it contains one or more compounds of the formula I.

contains
wherein

R ¹

a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, wherein in these radicals also one or more CH ₂ groups each independently of one another by -C≡C-, -CH = CH-, -O-, -CO -O- or -O-CO- may be replaced so that O atoms are not directly linked to each other,

Ring A

a left or right aligned ring system of the formulas

Z ¹ , Z ²

a single bond, -C≡C-, -CF = CF-, -CH = CH-, -CF ₂ O-, or -CH ₂ CH ₂ -, wherein at least one group of Z ¹ and Z ^{2 is} the group -CF = CF means

X

F, Cl, CN, SF ₅ or a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, wherein in these radicals also one or more CH ₂ groups each independently of one another by -C≡C-, -CH = CH, -O-, -CO-O- or -O-CO- can be replaced so that O atoms are not directly linked, and

L ¹ , L ² , L ³ , L ⁴ , L ⁵ and L ⁶

each independently of one another H or F, and

m

0 or 1,

mean,
and additionally one or more selected compounds of the general formulas K-1 to K-12:

wherein

R ⁰

n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 C atoms

means.

Preferably, 2, 3 or 4 of the substituents L ¹ , L ² , L ³ and L ⁴ in the formula I mean hydrogen and the remaining F. Particular preference is given to media with compounds of the formula I in which L ⁵ and L ⁶ = H. In the case where m = 0, L ¹ or L ² are particularly preferably F. In the case where m = 1, L ¹ and L ^{2 are more} preferably H. X is preferably F, Cl, OCF ₃ , CF ₃ , SF ₅ , OCHF ₂ , OC ₂ F ₅ , OC ₃ F ₇ , OCHFCF ₃ , OCF ₂ CHFCF ₃ or an alkyl radical having 1 to 8 C atoms. Very particular preference is given to compounds in which X is a substituent F, Cl, OCF ₃ or a straight-chain alkyl radical having 1 to 6 C atoms. R ¹ is preferably an unsubstituted, straight-chain 1-6 C alkyl or alkoxy radical or a corresponding 2-6 C alkenyl radical, very particularly a 1-6 C n- alkyl radical.

To obtain mixtures having a particularly high dielectric anisotropy, the substituent X preferably denotes F, Cl, OCF ₃ , CF ₃ , SF ₅ , OCHF ₂ , OC ₂ F ₅ , OC ₃ F ₇ , OCHFCF ₃ or OCF ₂ CHFCF ₃ , particularly preferably F, CF ₃ or OCF ₃ , and most preferably F or OCF ₃ .

The link Z ¹ preferably denotes a single bond or -CF = CF-. The link Z ² is preferably -CF = CF- or -CF ₂ O-.

Another object of the invention are compounds of formula I, wherein m is 1 and Z ^{2 is} a bridge -CF = CF- (compounds Ia). In the compounds of the formula I according to the invention, the other structural units R ¹ , ring A, Z ¹ , X and L ^{1-6 have} the meanings given above and the preferred meanings given above.

The compounds of the formula I have a wide range of applications. Depending on the choice of substituents, these compounds may serve as base materials from which liquid crystalline media are predominantly composed; however, it is also possible to add compounds of the formulas I to liquid-crystalline base materials from other classes of compounds in order, for example, to influence the dielectric and / or optical anisotropy of such a dielectric and / or to optimize its threshold voltage and / or its viscosity.

The compounds of the formula I are colorless in the pure state and form liquid-crystalline mesophases in a temperature range which is favorably located for the electro-optical use. Chemically and thermally, they are stable.

The compounds according to the invention, alone and in mixtures, have a particularly low rotational viscosity compared with other compounds having comparable physicochemical properties. In addition, they show very good overall properties, in particular with regard to the ratio of the rotational viscosity to the clearing point (γ1 / KIp.).

wobei die Ringe nach beiden Seiten ausgerichtet sein können.In the event that m = 1 and Z ^{1 is} a group -CF = CF-, the ring A is preferably a ring system selected from the formulas

wherein the rings can be aligned on both sides.

oder

insbesondere der Formeln

In the event that m = 1 and Z ^{2 is} a group -CF = CF-, the ring A is preferably a ring system selected from the formulas

or

in particular the formulas

m

1 bedeutet,

Z²

-CF=CF- und Z¹ eine Einfachbindung,

X

F, -OCF₃, -CF₃, CN, 1-6 C n-Alkyl, oder 1-6 C n-Alkoxy, insbesondere F oder -OCF₃,

L⁵, L⁶

H, oder

R¹

1-7 C Alkyl oder 2-7 C Alkylen

bedeutet.Preferred compounds according to the invention are characterized in that , independently of one another,

m

1 means

Z ²

-CF = CF- and Z ^{1 is} a single bond,

X

F, -OCF ₃ , -CF ₃ , CN, 1-6 C n -alkyl, or 1-6 C n -alkoxy, in particular F or -OCF ₃ ,

L ⁵ , L ⁶

H, or

R ¹

1-7 C alkyl or 2-7 C alkylene

means.

In the event that Z ^{2 is} a group -CF = CF-, L ³ and L ^{4 are} preferably H.

worin R¹, Ring A, X, L¹, L², L⁵ und L⁶ wie oben definiert sind.Particularly preferred compounds according to the invention are characterized in that exactly one group of Z ¹ and Z ^{2 represents} a group -CF = CF-. Consequently, particularly preferred compounds according to the invention are those of the general formula Ib:

wherein R ¹ , ring A, X, L ¹ , L ² , L ⁵ and L ^{6 are} as defined above.

Particularly preferred compounds of the formula I in which the ring A is a tetrahydroyran ring are compounds of the formula Ic:

If R ¹ in formula I denotes an alkyl radical and / or an alkoxy radical, this may be straight-chain or branched. Preferably, it is straight-chain, has 2, 3, 4, 5, 6 or 7 carbon atoms and thus preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, furthermore methyl , Octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octoxy, nonoxy, decoxy, undecoxy, dodecoxy, tridecoxy or tetradedoxy.

Oxaalkyl is preferably straight-chain 2-oxapropyl (= methoxymethyl), 2 - (= ethoxymethyl) or 3-oxabutyl (= 2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5- Oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6-, or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadexyl.

If R ^{1 is} an alkyl radical in which a CH ₂ group is replaced by -CH = CH-, this may be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. It therefore means especially vinyl, prop-1, or prop-2-enyl, but-1, 2- or but-3-enyl, pent-1, 2-, 3- or pent-4-enyl, hex 1-, 2-, 3-, 4- or hex-5-enyl, hept-1, 2-, 3-, 4-, 5- or hept-6-enyl, Oct-1, 2-, 3-, 4-, 5-, 6- or oct-7-enyl, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, Dec-1 -, 2-, 3-, 4-, 5-, 6-, 7-, 8- or dec-9-enyl.

If R ^{1 is} an alkyl radical in which one CH ₂ group is replaced by -O- and one by -CO-, these are preferably adjacent. Thus, they include an acyloxy group -CO-O- or an oxycarbonyl group -O-CO-. Preferably, these are straight-chain and have 2 to 6 carbon atoms.

They therefore mean especially acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 2-acetyloxypropyl, 3-propionyl-oxypropyl, 4-acetyl-oxybutyl, Methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethly, propoxycarbonylmethyl, butoxycarbonylmethyl, 2- (methoxycarbonyl) ethyl, 2- (ethoxycarbonyl) ethyl, 2- (propoxycarbonyl) -ethyl, 3- (methoxycarbonyl) -propyl, 3- (ethoxycarbonyl) -propyl or 4- (methoxycarbonyl) -butyl.

If R ^{1 is} an alkyl radical in which a CH ₂ group is replaced by unsubstituted or substituted -CH = CH- and an adjacent CH ₂ group by CO or CO-O or O-CO, this may be straight-chain or branched , It is preferably straight-chain and has 4 to 12 C atoms. It therefore particularly means acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, 10-acryloyloxydecyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3 Methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl, 8-methacryloyloxyoctyl, 9-methacryloyloxynonyl.

If R ^{1 is} an alkyl or alkenyl radical which is monosubstituted by CN or CF ₃ , this radical is preferably straight-chain. The substitution by CN or CF ₃ is in any position.

If R ^{1 is} an alkyl or alkenyl radical which is at least monosubstituted by halogen, this radical is preferably straight-chain and halogen is preferably F or Cl. In the case of multiple substitution, halogen is preferably F. The resulting radicals also include perfluorinated radicals. For single substitution, the fluoro or chloro substituent may be in any position, but preferably in the ω position.

Compounds with branched wing groups R ¹ can occasionally because of a better solubility in the usual liquid-crystalline Base materials of importance, but especially as chiral dopants, if they are optically active. Smectic compounds of this type are useful as components of ferroelectric materials.

Branched groups of this type usually contain no more than one chain branch. Preferred branched radicals R ¹ are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy.

If R ^{1 represents} an alkyl radical in which two or more CH ₂ groups have been replaced by -O- and / or -CO-O-, this may be straight-chain or branched. Preferably, it is branched and has 3 to 12 carbon atoms. It therefore particularly denotes bis-carboxy-methyl, 2,2-bis-carboxy-ethyl, 3,3-bis-carboxy-propyl, 4,4-bis-carboxy-butyl, 5,5-bis-carboxy-pentyl, 6,6-bis-carboxy-hexyl, 7,7-bis-carboxy-heptyl, 8,8-bis-carboxy-octyl, 9,9-bis-carboxy-nonyl, 10,10-bis-carboxy-decyl, Bis (methoxy-carbonyl) -methyl, 2,2-bis (methoxycarbonyl) -ethyl, 3,3-bis (methoxycarbonyl) -propyl, 4,4-bis (methoxycarbonyl) -butyl, 5, 5-bis (methoxycarbonyl) pentyl, 6,6-bis (methoxycarbonyl) hexyl, 7,7-bis (methoxycarbonyl) heptyl, 8,8-bis (methoxycarbonyl) octyl, Bis (ethoxycarbonyl) methyl, 2,2-bis (ethoxycarbonyl) ethyl, 3,3-bis (ethoxycarbonyl) propyl, 4,4-bis (ethoxycarbonyl) butyl, 5,5-bis (ethoxycarbonyl) -hexyl.

The compounds of the formulas I are prepared by methods known per se, as described in the literature (eg in the standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart), namely under Reaction conditions which are known and suitable for the said reactions. One can also make use of known per se, not mentioned here variants.

Suitable methods of preparation are outlined in Scheme 1 and Scheme 2.

Scheme 1 shows how the difluoroethene compounds 3 according to the invention can be prepared by palladium-catalyzed linking of a chlorodifluoroethene compound of the formula 1 with a boronic acid compound of the formula 2 . The formula 3 is analogous to formula I. The radicals Ar ¹ and Ar ² represent correspondingly substituted, aromatic ring systems.

The starting compounds of formula 1 can be prepared from an aryl halide 4 by halogen-metal exchange and reaction with chlorotrifluoroethylene. In the synthesis strategy shown, the desired E- isomer of the formula 3 is obtained in excess of the Z isomer. The desired isomer can be readily isolated by chromatography and crystallization.

The invention also electro-optical displays (in particular STN or MFK displays with two plane-parallel support plates, which form a cell with a border, integrated non-linear elements for switching individual pixels on the support plates and an in-cell nematic liquid crystal composition having positive dielectric anisotropy and high resistivity) containing such media and the use of these media for electro-optical purposes.

The liquid-crystal mixtures according to the invention enable a significant expansion of the available parameter space. The achievable combinations of clearing point, low temperature viscosity, thermal stability and dielectric anisotropy far surpass existing prior art materials.

The compounds of formula I according to the invention with further highly polar components with Δε> 8 and with one or more neutral components (-1.5 <Δε <3), which - at least in part - at the same time a low optical anisotropy (Δn <0.08 ) combined to obtain the liquid crystalline media.

The liquid-crystal mixtures according to the invention make it possible, while maintaining the nematic phase to -20 ° C and preferably to -30 ° C, particularly preferably to -40 ° C, a clearing point above 60 ° C, preferably above 65 ° C, more preferably above 70 ° C. simultaneously achieving dielectric anisotropy values Δ∈ ≥ 3, preferably ≥ 5, in particular also ≥ 7 and a high value for the specific resistance, whereby excellent STN and MFK displays can be achieved. In particular, the mixtures are characterized by very low rotational viscosities. The rotational viscosities γ ₁ are below 90 mPa · s, preferably below 80 mPa · s, more preferably below 70 mPa · s. The operating voltages are simultaneously low, depending on the chosen dielectric anisotropy of the medium.

It is understood that by suitable choice of the components of the mixtures according to the invention also higher clearing points (eg above 90 ° C) can be realized at higher threshold voltages or lower clearing points at lower threshold voltages to obtain the other advantageous properties. Likewise, in accordance with little increased viscosities mixtures with larger Δε and thus low thresholds or mixtures with higher clearing points can be obtained. The MFK displays according to the invention preferably operate in the first transmission minimum according to Gooch and Tarry [ CH Gooch and HA Tarry, Electron. Lett. 10, 2-4, 1974 ; CH Gooch and HA Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975 ], where in addition to particularly favorable electro-optical properties, such as high slope of the characteristic and low angle dependence of the contrast ( DE 3022818 A1 ) at the same threshold voltage as in an analog display in the second minimum, a smaller dielectric anisotropy is sufficient. As a result, significantly higher specific resistances can be achieved using the mixtures according to the invention in the first minimum than in the case of mixtures with cyano compounds. By suitable choice of the individual components and their proportions by weight, the person skilled in the art can set the birefringence required for a given layer thickness of the MFK display with simple routine methods.

The flow viscosity ν ₂₀ at 20 ° C is preferably <60 mm ² · s ^-1 , more preferably <50 mm ² · s ^-1 . The rotational viscosity γ _{1 of} the mixtures according to the invention at 20 ° C. is preferably <80 mPa · s, more preferably <70 mPa · s. The nematic phase range preferably has a width of at least 90 ° C, in particular of at least 100 ° C. Preferably, this range extends at least from -20 ° to + 70 ° C.

For liquid crystal displays, a small switching time is desired. This is especially true for video playback ads. For such displays, switching times (sum: t _on + t _off ) of a maximum of 16 ms are required. The upper limit of the switching time is determined by the refresh rate. In addition to the rotational viscosity γ ₁ , the tilt angle also influences the switching time.

oder Ester der Formel R

Measurements of the Voltage Holding Ratio (HR) [ S. Matsumoto et al., Liquid Crystals 5, 1320 (1989 ); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984 ); G. Weber et al., Liquid Crystals 5, 1381 (1989 )] have shown that mixtures according to the invention comprising compounds of the formula I a significantly smaller decrease in the HR with increasing temperature as analogous mixtures containing instead of the compounds of formula I cyanophenylcyclohexanes of the formula

or esters of the formula R

worin R¹ die in Formel I angegebene Bedeutung hat.Particularly preferred liquid-crystalline media contain one or more compounds of the formulas I-1 to I-30:

wherein R ^{1 has} the meaning given in formula I.

Of these preferred compounds, particularly preferred among compounds having two rings (m = 0) are those of the formulas I-1, I-2, I-3, I-4 and I-5, more particularly those of the formulas I-1, I -2 and I-4. Particularly preferred among the three-ring compounds are those of the formulas I-7, I-8, I-10, I-13, I-14, I-16, I-19, I-22, I-23, I-24, I -27 and I-28, especially those of formulas I-8 and I-14.

• Das flüssigkristallines Medium ist dadurch gekennzeichnet, dass der Anteil an Verbindungen der Formel I im Gesamtgemisch 0,5 bis 40 Gew.% beträgt; bevorzugt beträgt er 4 bis 20 Gew.%.
• Das Medium enthält ein, zwei oder mehrere Verbindungen der Formeln I-1 bis I-30;
• Das Medium enthält zusätzlich eine oder mehrere Verbindungen ausgewählt aus der Gruppe bestehend aus den allgemeinen Formeln II bis VI:
  
  
  
  
  
  worin die einzelnen Reste die folgenden Bedeutungen haben:

  R⁰

  n-Alkyl, Alkoxy, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen,

  X⁰

  F, Cl, halogeniertes Alkyl, halogeniertes Alkenyl, halogeniertes Oxalkyl, halogeniertes Alkenyloxy oder halogeniertes Alkoxy mit bis zu 6 C-Atomen,

  Z⁰

  -C₂F₄-, -CF=CF-, -C₂H₄-, -(CH₂)₄-, -OCH₂-, -CH₂O-, -CF₂O- oder -OCF₂-,

  Y¹ bis Y⁴

  jeweils unabhängig voneinander H oder F,

  r

  0 oder 1, und

  t

  0, 1 oder 2.

Preferred embodiments of the liquid-crystalline media according to the invention are given below:

• The liquid-crystalline medium is characterized in that the proportion of compounds of the formula I in the total mixture is 0.5 to 40% by weight; it is preferably 4 to 20% by weight.
• The medium contains one, two or more compounds of the formulas I-1 to I-30;
• The medium additionally contains one or more compounds selected from the group consisting of the general formulas II to VI:
  
  
  
  
  
  in which the individual radicals have the following meanings:

  R ⁰

  n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl having in each case up to 9 C atoms,

  X ⁰

  F, Cl, halogenated alkyl, halogenated alkenyl, halogenated oxalkyl, halogenated alkenyloxy or halogenated alkoxy having up to 6 C atoms,

  Z ⁰

  -C ₂ F ₄ -, -CF = CF-, -C ₂ H ₄ -, - (CH ₂ ) ₄ -, -OCH ₂ -, -CH ₂ O-, -CF ₂ O- or -OCF ₂ -,

  Y ¹ to Y ⁴

  each independently of one another H or F,

  r

  0 or 1, and

  t

  0, 1 or 2.

oder

• Das Medium enthält zusätzlich eine oder mehrere Verbindungen ausgewählt aus der Gruppe bestehend aus den allgemeinen Formeln VII bis XIII:
  
  
  
  
  
  
  
  worin

  R⁰

  n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen,

  X⁰

  F, Cl, halogeniertes Alkyl, halogeniertes Alkenyl, halogeniertes Alkenyloxy oder halogeniertes Alkoxy mit bis zu 6 C-Atomen, und

  Y¹ bis Y⁴

  jeweils unabhängig voneinander H oder F

bedeutet.The compound of formula IV is preferred

or

• The medium additionally contains one or more compounds selected from the group consisting of the general formulas VII to XIII:
  
  
  
  
  
  
  
  wherein

  R ⁰

  n-alkyl, oxaalkyl, fluoroalkyl or alkenyl having in each case up to 9 C atoms,

  X ⁰

  F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkenyloxy or halogenated alkoxy having up to 6 C atoms, and

  Y ¹ to Y ⁴

  each independently of one another H or F.

means.

X ⁰ here is preferably F, Cl, CF ₃ , OCF ₃ or OCHF ₂ . R ⁰ here preferably denotes alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

worin

R⁰

n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen

bedeutet.

• Der Anteil an Verbindungen der Formel I beträgt im Gesamtgemisch 0,5 bis 40 Gew.%, besonders bevorzugt 1 bis 30 Gew.%;
• Der Anteil der Verbindungen der Formeln E-a bis E-d ist vorzugsweise 5-30 Gew.%, insbesondere 5-25 Gew.%;
• Der Anteil an Verbindungen der Formeln I bis VI zusammen beträgt im Gesamtgemisch mindestens 30 Gew.%;
• Der Anteil an Verbindungen der Formeln II bis VI im Gesamtgemisch beträgt 30 bis 80 Gew.%;
  
  ist vorzugsweise
  
  
  
  
• Das Medium enthält Verbindungen der Formeln II, III, IV, V und/oder VI;
• R⁰ ist in allen Verbindungen bevorzugt geradkettiges Alkyl oder Alkenyl mit 2 bis 7 C-Atomen;
• Das Medium enthält weitere Verbindungen aus der Klasse der fluorierten Terphenyle mit R⁰ und/oder X⁰, wie unten definiert, als Endgruppen, vorzugsweise ausgewählt aus der folgenden Gruppe bestehend aus den allgemeinen Formeln XIV und XV:
  
  
  worin

  R⁰

  n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen,

  X⁰

  F, Cl, halogeniertes Alkyl, halogeniertes Alkenyl, halogeniertes Alkenyloxy oder halogeniertes Alkoxy mit bis zu 6 C-Atomen, und

  Ring B und C,

  unabhängig voneinander, 1,4-Phenylen mit 0, 1, oder 2 Fluor substituiert,

bedeutet.The medium additionally contains one or more compounds of the formulas Ea to Ed

wherein

R ⁰

n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms

means.

• The proportion of compounds of formula I is in the total mixture 0.5 to 40 wt.%, Particularly preferably 1 to 30 wt.%;
• The proportion of the compounds of the formulas Ea to Ed is preferably 5-30% by weight, in particular 5-25% by weight;
• The proportion of compounds of the formulas I to VI together in the total mixture is at least 30% by weight;
• The proportion of compounds of the formulas II to VI in the total mixture is 30 to 80% by weight;
  
  is preferable
  
  
  
  
• The medium contains compounds of the formulas II, III, IV, V and / or VI;
• R ⁰ in all compounds is preferably straight-chain alkyl or alkenyl having 2 to 7 C atoms;
• The medium contains further compounds from the class of fluorinated terphenyls with R ⁰ and / or X ⁰ , as defined below, as end groups, preferably selected from the following group consisting of the general formulas XIV and XV:
  
  
  wherein

  R ⁰

  n-alkyl, oxaalkyl, fluoroalkyl or alkenyl having in each case up to 9 C atoms,

  X ⁰

  F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkenyloxy or halogenated alkoxy having up to 6 C atoms, and

  Ring B and C,

  independently of one another, 1,4-phenylene is substituted by 0, 1 or 2 fluorine,

means.

Preferably in formula XIV and XV at least one of the 1,4-phenylene rings is monosubstituted or polysubstituted by fluorine atoms. In compounds of the formula XIV, two of the phenylenes are preferably substituted by at least one fluorine atom or one of the phenylenes is substituted by 2 fluorine atoms; In compounds of the formula XV, one of the phenylenes is preferably substituted by at least one fluorine atom. X ⁰ here is preferably F, Cl, CF ₃ , OCF ₃ or OCHF ₂ . R ⁰ here preferably denotes alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

worin R⁰ jeweils unabhängig voneinander wie für die Formel XIV definiert ist.

• Der Anteil der Verbindungen der Formeln XIV und XV ist vorzugsweise 0-25 Gew.%, insbesondere 2-20 Gew.% und ganz besonders 5-15 Gew.%;

The compounds of the formula XIV are preferably compounds of the formulas XIV-1 to XIV-5:

wherein each R ⁰ is independently defined as for the formula XIV.

• The proportion of the compounds of the formulas XIV and XV is preferably 0-25% by weight, in particular 2-20% by weight and very particularly 5-15% by weight;

worin R⁰ wie für die Formel XV definiert ist.

• Das Medium enthält weitere Verbindungen, vorzugsweise ausgewählt aus der folgenden Gruppe bestehend aus den allgemeinen Formeln XVI bis XVIII:
  
  
  
  worin

  R⁰

  n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen,

  Y¹

  H oder F, und

  X⁰

  F, Cl, halogeniertes Alkyl, halogeniertes Alkenyl, halogeniertes Alkenyloxy oder halogeniertes Alkoxy mit bis zu 6 C-Atomen

  bedeutet;
  die 1,4-Phenylenringe können zusätzlich durch CN, Chlor oder Fluor substituiert sein. Vorzugsweise sind die 1,4-Phenylenringe ein- oder mehrfach durch Fluoratome substituiert.
• Das Medium enthält zusätzlich ein, zwei, drei oder mehr, vorzugsweise zwei oder drei Verbindungen der Formeln
  
  
  worin "Alkyl" und "Alkyl*" die nachfolgend angegebene Bedeutung haben. Der Anteil der Verbindungen der Formeln O1 und/oder 02 in den erfindungsgemäßen Mischungen beträgt vorzugsweise 0-15 Gew.%, insbesondere 1-12 Gew.% und ganz besonders bevorzugt 3-10 Gew.%.
• Das Medium enthält vorzugsweise 5-35 Gew.% der Verbindung IVa.
• Das Medium enthält vorzugsweise ein, zwei oder drei Verbindungen der Formel IVa, worin X^o F oder OCF₃ bedeutet.
• Das Medium enthält vorzugsweise eine oder mehrere Verbindungen der Formeln IIa bis IIg,
  
  
  
  
  
  
  

worin

R⁰

n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen

bedeutet.The compounds of the formula XV are preferably a compound of the formula XV-1:

wherein R ^{0 is} as defined for the formula XV.

• The medium contains further compounds, preferably selected from the following group consisting of the general formulas XVI to XVIII:
  
  
  
  wherein

  R ⁰

  n-alkyl, oxaalkyl, fluoroalkyl or alkenyl having in each case up to 9 C atoms,

  Y ¹

  H or F, and

  X ⁰

  F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkenyloxy or halogenated alkoxy having up to 6 C atoms

  means;
  The 1,4-phenylene rings may additionally be substituted by CN, chlorine or fluorine. Preferably, the 1,4-phenylene rings are mono- or polysubstituted by fluorine atoms.
• The medium additionally contains one, two, three or more, preferably two or three compounds of the formulas
  
  
  wherein "alkyl" and "alkyl *" have the meaning given below. The proportion of the compounds of the formulas O1 and / or O 2 in the mixtures according to the invention is preferably 0-15% by weight, in particular 1-12% by weight and very particularly preferably 3-10% by weight.
• The medium preferably contains 5-35% by weight of compound IVa.
• The medium preferably contains one, two or three compounds of formula IVa, wherein X ^{o is} F or OCF ₃ .
• The medium preferably contains one or more compounds of the formulas IIa to IIg,
  
  
  
  
  
  
  

wherein

R ⁰

n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms

means.

• Der Anteil an Verbindungen der Formeln K (K-1 bis K-12) beträgt bevorzugt 5 bis 50 Gew-%, besonders bevorzugt 10 bis 40 Gew.%.
• Der Anteil der Verbindungen der Formel IVb und/oder IVc, worin X^o Fluor und R⁰ CH₃, C₂H₅, n-C₃H₇, n-C₄H₉ oder n-C₅H₁₁ bedeutet, beträgt im Gesamtgemisch 2 bis 20 Gew.%, insbesondere 2 bis 15 Gew.%.
• Das Medium enthält vorzugsweise Verbindungen der Formeln II bis VI, worin R⁰ Methyl bedeutet. Besonders bevorzugt enthält das erfindungsgemäße Medium Verbindungen der Formeln
  
  
  
  
• Das Medium enthält vorzugsweise ein, zwei oder mehr, vorzugsweise ein oder zwei, Dioxan-Verbindungen der Formeln,
  
  

worin

R⁰

n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen

bedeutet.In the compounds of the formulas IIa-IIg, R ^{0 is} preferably methyl, ethyl, n-propyl, n-butyl and n-pentyl.

• The proportion of compounds of the formulas K (K-1 to K-12) is preferably from 5 to 50% by weight, particularly preferably from 10 to 40% by weight.
• The proportion of the compounds of the formula IVb and / or IVc in which X ^{o is} fluorine and R ^{0 is} CH ₃ , C ₂ H ₅ , nC ₃ H ₇ , nC ₄ H ₉ or nC ₅ H ₁₁ is 2 to 20% by weight in the total mixture .%, In particular 2 to 15 wt.%.
• The medium preferably contains compounds of the formulas II to VI, in which R ^{0 is} methyl. The medium according to the invention particularly preferably contains compounds of the formulas
  
  
  
  
• The medium preferably contains one, two or more, preferably one or two, dioxane compounds of the formulas,
  
  

wherein

R ⁰

n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms

means.

• Das Medium enthält vorzugsweise ein, zwei oder mehr, vorzugsweise ein oder zwei Pyranverbindungen der Formeln P-1 bis P-4,
  
  
  
  
  worin

  R⁰

  n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen

  bedeutet.
• Das Medium enthält zusätzlich ein, zwei oder mehr Zweikern-Verbindungen der Formeln Z-1 bis Z-9 (allgemein Z),
  
  
  
  
  
  
  
  
  

worin

R^1a und R^2a

jeweils unabhängig voneinander H, CH₃, C₂H₅ oder n-C₃H₇ bedeuten, und

R⁰

n-Alkyl, Oxaalkyl, Fluoralkyl oder Alkenyl mit jeweils bis zu 9 C-Atomen

bedeutet.The proportion of the dioxane compounds D-1 and / or D-2 in the mixtures according to the invention is preferably 0-25% by weight, in particular 0-20% by weight and very particularly preferably 0-15% by weight.

• The medium preferably contains one, two or more, preferably one or two pyran compounds of the formulas P-1 to P-4,
  
  
  
  
  wherein

  R ⁰

  n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms

  means.
• The medium additionally contains one, two or more dinuclear compounds of the formulas Z-1 to Z-9 (generally Z),
  
  
  
  
  
  
  
  
  

wherein

R ^1a and R ^2a

each independently of one another are H, CH ₃ , C ₂ H ₅ or nC ₃ H ₇ , and

R ⁰

n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms

means.

Alkyl, alkyl * and alkenyl have the meanings given below.

• Der Anteil an Verbindungen der Formeln Z-1 bis Z-9 beträgt insgesamt 5 bis 70 Gew.%, bevorzugt 15 bis 50 Gew.%. Der Anteil an Verbindungen der Formel Z-5 für sich beträgt vorzugsweise 10 bis 60 Gew.%, bevorzugt 15 bis 50 Gew.%.
• Das Medium besteht im wesentlichen aus Verbindungen ausgewählt aus der Gruppe bestehend aus den allgemeinen Formeln I bis VI, K-1 bis K-121 und aus Z-1 bis Z-9.

Of the two-core compounds mentioned, particular preference is given to the compounds Z-2, Z-5, Z-4 and Z-6, in particular the compounds of the formula Z-5 with alkyl being propyl and R ^1a being H or methyl, in particular with R ^1a is H.

• The proportion of compounds of the formulas Z-1 to Z-9 is in total 5 to 70% by weight, preferably 15 to 50% by weight. The proportion of compounds of the formula Z-5 per se is preferably from 10 to 60% by weight, preferably from 15 to 50% by weight.
• The medium consists essentially of compounds selected from the group consisting of the general formulas I to VI, K-1 to K-121 and from Z-1 to Z-9.

wobei t jeweils unabhängig 0, 1 oder 2 ist,
und ganz besonders der Formel

wobei n 1 bis 8 ist.

• Das Medium enthält zusätzlich ein, zwei oder mehr Verbindungen mit anellierten Ringen der Formeln AN1 bis AN11:
  
  
  
  
  
  
  
  
  (L = H oder F)
  
  
  
  worin R⁰ die oben angegebenen Bedeutungen hat;
• Die erfindungsgemäßen Mischungen zeichnen sich insbesondere dadurch aus, dass sie Klärpunkte von ≥ 70 °C und Schwellenspannungen von < 2,0 V aufweisen.
• Die erfindungsgemäßen Mischungen zeichnen sich insbesondere dadurch aus, dass sie eine dielektrische Anisotropie von Δε > 3 und bevorzugt von Δε > 5 aufweisen.

The medium additionally contains one or more UV-stabilizing compounds, in particular a quaterphenyl compound. Particularly preferred are mono- or polyfluorinated quaterphenyl compounds of the formula

where each t is independently 0, 1 or 2,
and especially the formula

where n is 1 to 8.

• The medium additionally contains one, two or more compounds with fused rings of the formulas AN1 to AN11:
  
  
  
  
  
  
  
  
  (L = H or F)
  
  
  
  wherein R ^{0 has} the meanings given above;
• The mixtures according to the invention are distinguished, in particular, by having clearing points of .gtoreq.70.degree. C. and threshold voltages of <2.0 V.
• The mixtures according to the invention are distinguished, in particular, by having a dielectric anisotropy of Δε> 3 and preferably of Δε> 5.

It has been found that even a relatively small proportion of compounds of the formula I in admixture with conventional liquid crystal materials, but in particular with one or more compounds of the formulas K, Z, II, III, IV, V and / or VI to a considerable reduction of the Rotation viscosities and the switching times leads, at the same time broad nematic phases are observed with low transition temperatures smectic-nematic, whereby the storage stability is improved.

The term "alkyl" or "alkyl *" embraces straight-chain and branched alkyl groups having 1-7 carbon atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl, hexyl and heptyl. Groups of 1-5 carbon atoms are generally preferred.

The term "alkenyl" includes straight-chain and branched alkenyl groups having 2-7 carbon atoms, especially the straight-chain groups. Preferred alkenyl groups are C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ -EE-alkenyl, C ₅ -C ₇ -alkenyl, C ₆ -C ₇ -5-alkenyl and C ₇ -6-alkenyl, in particular C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ -EE-alkenyl and C ₅ -C ₇ -4 alkenyl. Examples of particularly preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4- Pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and the like. Groups of up to 5 carbon atoms are generally preferred.

The term "fluoroalkyl" preferably includes straight-chain fluoro-terminated groups, i. Fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. Other positions of the fluorine are not excluded.

The term "oxaalkyl" or "alkoxy" preferably comprises straight-chain radicals of the formula C _n H _{2n + 1} -O- (CH ₂ ) _m , in which n and m are each independently of one another from 1 to 6. m can also mean 0. Preferably, n = 1 and m is 1-6 or m = 0 and n = 1-3.

By suitably selecting the meanings of R ⁰ and X ⁰ , the response times, the threshold voltage, the transconductance of the transmission characteristics etc. can be modified in the desired manner. For example, 1 E-alkenyl radicals, 3E-alkenyl radicals, 2E-alkenyloxy radicals and the like usually lead to shorter response times, improved nematic tendencies and a higher ratio of the elastic constants k ₃₃ (bend) and k ₁₁ (splay) in comparison to alkyl resp Alkoxy radicals. 4-Alkenyl radicals, 3-alkenyl radicals and the like generally give lower threshold voltages and smaller values of k ₃₃ / k ₁₁ compared to alkyl and alkoxy radicals.

A -CH ₂ CH ₂ group generally results in higher values of k ₃₃ / k ₁₁ compared to a single covalent bond. Higher values of k ₃₃ / k ₁₁ facilitate, for example, flatter transmission characteristic lines in TN cells with a 90 ° twist (for achieving gray shades) and steeper transmission characteristic lines in STN, SBE and OMI cells (greater multiplexing) and vice versa.

The optimum ratio of the compounds of the formulas I and K + Z + II + III + IV + V + VI depends largely on the desired properties, on the choice of the components of the formulas I, II, III, IV, V and / or VI and the choice of other optionally present components.

Suitable proportions within the range given above can be easily determined on a case-by-case basis.

The total amount of compounds of the formulas I and the cocomponents given in the mixtures according to the invention is not critical. The mixtures may therefore contain one or more other components to optimize various properties. The observed effect on the response times and the threshold voltage, however, is generally greater the higher the total concentration of compounds of the formulas I and the cocomponents indicated.

In a particularly preferred embodiment, the media according to the invention contain compounds of the formula II to VI (preferably II, III and / or IV, in particular IVa) in which X is ⁰ F, OCF ₃ , OCHF ₂ , OCH = CF ₂ , OCF = CF ₂ or OCF ₂ -CF ₂ H means. A favorable synergistic effect with the compounds of the formula I leads to particularly advantageous properties. In particular, mixtures containing compounds of the formula I and of the formula IVa are distinguished by their low threshold voltage.

The individual compounds that can be used in the media of the invention are either known or can be prepared analogously to the known compounds.

The structure of the MFK display of polarizers, electrode base plates and electrodes with surface treatment according to the invention corresponds to the usual construction for such displays. Here, the term of the usual construction is broad and includes all modifications and modifications of the MFK display, in particular matrix display elements based on poly-Si TFT or MIM.

However, a significant difference of the displays of the invention on the basis of the usual twisted nematic cell is the choice of the liquid crystal parameters of the liquid crystal layer.

The preparation of the liquid crystal mixtures which can be used according to the invention is carried out in a conventional manner. In general, the desired amount of the components used in a lesser amount is dissolved in the component making up the main constituent, advantageously at elevated temperature. It is also possible solutions of the components in an organic solvent, e.g. in acetone, chloroform or methanol, and to remove the solvent again after thorough mixing, for example by distillation.

The dielectrics may also other, known in the art and described in the literature additives such. As UV stabilizers such as Tinuvin ^® Fa. Ciba, antioxidants, radical scavengers, etc. included. For example, 0-15% pleochroic dyes or chiral dopants may be added. Suitable stabilizers and dopants are mentioned below in Tables C and D.

The threshold voltage V ₁₀ denotes the voltage for 10% transmission (viewing direction perpendicular to the plate surface). t _on denotes the switch-on time and t _off the switch-off time at an operating voltage corresponding to 2.0 times the value of V ₁₀ . Δn denotes the optical anisotropy. Δε denotes the dielectric anisotropy (Δε = Δε ∥ _{-ε ⊥} , where ε _{∥ means} the dielectric constant parallel to the _longitudinal molecular _axes and ε _⊥ the dielectric constant perpendicular thereto). The electro-optical data are measured in a TN cell in the 1st minimum (ie at a d · Δn value of 0.5 microns) at 20 ° C, unless expressly stated otherwise. The optical data are measured at 20 ° C, unless expressly stated otherwise.

In the present application and in the following examples, the structures of the liquid crystal compounds are indicated by acronyms, wherein the transformation into chemical formulas according to the following Tables A and B takes place. All radicals C _n H _{2n + 1} and C _m H _{2m + 1} are straight-chain alkyl radicals with n or m C atoms; n and m are integers and are preferably 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. The coding according to Table B is self-evident. In Table A is only the acronym for the main body specified. In individual cases, a code for the substituents R ^{1 *} , R ^{2 *} , L ^{1 *} and L ^{2 *} follows separately from the acronym for the main body with a dash: Code for R ^{1 *} , R ^{2 *} , L ^{1 *} , L ^{2 *} , L ^{3 *} R ^{1 *} R ^{2 *} L ^{1 *} L ^{2 *} nm C _n H _{2n + 1} C _m H _{2m + 1} H H N0M OC _n H _{2n + 1} C _m H _{2m + 1} H H n0.m C _n H _{2n + 1} OC _m H _{2m + 1} H H n C _n H _{2n + 1} CN H H nN.F C _n H _{2n + 1} CN F H nN.FF C _n H _{2n + 1} CN F F nF C _n H _{2n + 1} F H H n Cl C _n H _{2n + 1} Cl H H n0F OC _n H _{2n + 1} F H H nF.F C _n H _{2n + 1} F F H nF.FF C _n H _{2n + 1} F F F NMF C _n H _{2n + 1} C _m H _{2m + 1} F H n0CF ₃ C _n H _{2n + 1} OCF ₃ H H n0CF ₃ .F C _n H _{2n + 1} OCF ₃ F H n0CF ₃ .FF C _n H _{2n + 1} OCF ₃ F F n-Vm C _n H ₂ n + 1 -CH = CH-C _m H _{2m + 1} H H nV-Vm C _n H _{2n + 1} -CH = CH- -CH = CH-C _m H _{2m + 1} H H

PYP

PYRP

BCH

CBC

CCH

CCP

CPTP

CEPTP

ECCP

CECP

EPCH

PCH

PTP

BECH

EBCH

CPC

B

FET-nF

CGG

CGU

CFU Tabelle B

BCH-n.Fm

CFU-n-F

CBC-nmF

ECCP-nm

CCZU-n-F

PGP-n-m

CGU-n-F

CDU-n-F

DCU-n-F

CGG-n-F

CPZG-n-OT

CC-nV-Vm

CCP-Vn-m

CCG-V-F

CCP-nV-m

CCP-V-m

CC-n-V

CCQU-n-F

CC-n-V1

CCQG-n-F

CQCU-n-F

Dec-U-n-F

CWCU-n-F

CWCG-n-F

CCOC-n-m

CPTU-n-F

GPTU-n-F

PQU-n-F

PUQU-n-F

PGU-n-F

PPGU-n-F

CGZP-n-OT

CCGU-n-F

CCQU-n-F

CUQU-n-F

APUQU-n-F

PP-n-2Vm Preferred mixture components are given in Tables A and B. <b><u> Table A </ u></b>

PYP

PYRP

BCH

CBC

CCH

CCP

CPTP

CEPTP

ECCP

CECP

EPCH

PCH

PTP

Bech

EBCH

CPC

B

FET nF

CGG

CGU

CFU

BCH-n.Fm

CFU-nF

CBC NMF

ECCP-nm

CCZU-nF

PGP nm

CGU-nF

CDU nF

DCU nF

CGG nF

CPZG-n-OT

CC-nV-Vm

CCP-Vn-m

CCG-VF

CCP-nV-m

CCP Vm

CC-nV

CCQU-nF

CC-n-V1

CCQG nF

CQCU nF

Dec-UnF

CWCU nF

CWCG nF

CCOC nm

CPTU nF

GPTU nF

PQU nF

PUQU nF

PGU-nF

PPGU nF

CGZP-n-OT

CCGU-nF

CCQU-nF

CUQU nF

APUQU nF

PP-n-2Vm

C 15

CB 15

CM 21

R/S-811

CM 44

CM 45

CM 47

R/S-1011

R/S-3011

CN

R/S-2011

R/S-4011

R/S-5011 Tabelle D Stabilisatoren, die beispielsweise den erfindungsgemäßen Mischungen zugesetzt werden können, werden nachfolgend genannt.

Particular preference is given to liquid-crystalline mixtures which, in addition to the compounds of the formulas I, contain at least one, two, three or four compounds from Table B. <b><u> Table C </ u></b> In Table C possible dopants are given, which are usually added to the mixtures of the invention. Preferably, the mixtures contain 0-10 wt.%, In particular 0.01-5 wt.% And particularly preferably 0.01-3 wt.% Of dopants.

C 15

CB 15

CM 21

R / S-811

CM 44

CM 45

CM 47

R / S-1011

R / S-3011

CN

R / S 2011

R / S-4011

R / S-5011 Stabilizers which can be added, for example, to the mixtures according to the invention are mentioned below.

The following examples illustrate the invention without limiting it. The person skilled in the art will be able to refer to the examples particularly suitable, unspecified embodiments and adapt them to different boundary conditions.

Above and below, percentages are by weight. All temperatures are in degrees Celsius. K = crystalline state, N = nematic phase, Sm = smectic phase and I = isotropic phase. The information between these symbols represents the transition temperatures for the pure substances.

The physical measurement methods on mixtures are described in " Merck Liquid Crystals, Physical Properties of Liquid Crystals ", Nov. 1997, Merck KGaA ,

The dielectric anisotropy Δε of the individual substances is determined at 20 ° C and 1 kHz. 10% by weight of the substances to be investigated are dissolved in the dielectrically positive mixture ZLI-4792 (Merck KGaA) and the measured value extrapolated to a concentration of 100%. The optical anisotropy Δn is determined at 20 ° C and a wavelength of 589.3 nm. It is also determined by extrapolation of the values at 10% by weight.

Klp.

Klärpunkt (Phasenübergangstemperatur nematisch-isotrop),

Δn

optische Anisotropie (589 nm, 20°C),

Δε

dielektrische Anisotropie (1 kHz, 20°C), ε_∥ - ε_⊥

ε_∥

Anteil der Dielektrizitätskonstante parallel zur Moleküllängsachse (1 kHz, 20 °C),

ε_⊥

Anteil der Dielektrizitätskonstante senkrecht zur Moleküllängsachse (1 kHz, 20 °C)

γ₁

Rotationsviskosität (20°C),

t_store

Tieftemperatur-Lagerstabilität in Stunden (-20°C, -30°C, -40°C),

V₁₀

Schwellenspannung = charakteristische Spannung bei einem relativen Kontrast von 10 %,

V₉₀

Sättigungsspannung = charakteristische Spannung bei einem relativen Kontrast von 90 %,

k₁

elastische Konstante Spreizdeformation (splay deformation, auch k₁₁)

k₃

elastische Konstante Biegedeformation (bend deformation, auch k₃₃)

k₃/k₁

Verhältnis von k₃ zu k₁,

V₀

kapazitive bzw. Freederickzs-Schwellenspannung

It means:

Klp.

Clearing point (phase transition temperature nematic-isotropic),

.DELTA.n

optical anisotropy (589 nm, 20 ° C.),

Δε

dielectric anisotropy (1 kHz, 20 ° C), ε _∥ - ε _⊥

ε _∥

Proportion of the dielectric constant parallel to the molecular axis (1 kHz, 20 ° C),

ε _⊥

Proportion of the dielectric constant perpendicular to the molecular longitudinal axis (1 kHz, 20 ° C)

γ ₁

Rotational viscosity (20 ° C),

t _store

Cryogenic storage stability in hours (-20 ° C, -30 ° C, -40 ° C),

V ₁₀

Threshold voltage = characteristic voltage at a relative contrast of 10%,

V ₉₀

Saturation voltage = characteristic voltage at a relative contrast of 90%,

k ₁

Spreizdeformation elastic constant (splay deformation, also k ₁₁₎

k ₃

elastic constant bending deformation (also k ₃₃ )

k ₃ / k ₁

Ratio of k ₃ to k ₁ ,

V ₀

capacitive or Freederickzs threshold voltage

Synthesis Example 1.1

By slow addition of 141 g (70.9 mmol) of 1-bromo-4-propylbenzene to 20 g (823 mmol) of magnesium in 200 ml of dry THF, a Grignard solution is prepared. After stirring for 1 h under reflux, it is diluted with 1 l of THF and cooled to -35 ° C. 100 g (0.86 mol) of chlorotrifluoroethylene are slowly introduced into the dry ice cooler and stirred for 1.5 h. The reaction solution is warmed to RT, stirred for 12 h and stirred into a mixture of ice / 2N HCl. The organic phase is separated off. The aqueous phase is extracted with MTB ether. The combined organic phases are washed with water and NaCl solution, dried and concentrated. The product is a colorless liquid.

Synthesis Example 1.2

2.02 g (30 mmol) of bis (tricyclohexylphosphine) palladium (II) chloride and 0.154 ml (30 mmol) of hydrazinium hydroxide are added under nitrogen to 18.2 g (97 mmol) of sodium orthosilicate in 50 ml of water and stirred for 5 min. 32.5 g (142 mmol) of the product from Example 1.1 and 50 g (141 mmol) of the boronic acid compound are added thereto and the mixture is stirred at reflux for 12 h. Then the organic phase is separated off, the residue is shaken out and all organic phases are combined. The purification is carried out by fractionation over 1 l of silica gel with pentane. The product fraction is crystallized from cold isopropanol. Colorless crystals (mp 55 ° C,> 99% GC / HPLC). K 55 N 75 I.

Synthesis Example 2

To 3.75 g (19.9 mmol) of sodium orthosilicate in 10 ml of water are added under nitrogen 0.40 g (0.72 mmol) of bis (tricyclohexylphosphine) palladium (II) chloride and 0.35 ml (0.72 mmol) of hydrazinium chloride were added and stirred for 5 min. To this are added 7.23 g (28 mmol) of the boronic acid and 7.50 g (27 mmol) of the chlorodifluoroethene compound and stirred at reflux for 12 h. After work-up analogously to Example 1.1 is crystallized from toluene / methanol (mp 39 ° C,> 99% GC / HPLC). K 39 SmB 110 SmA 221 N 226 I. Klp. 215.5 ° C Δε 8.4 .DELTA.n 0.223 γ ₁ 249 mPa · s

Mixing Example 1

CC-3-V 26% Clearing point [° C]: 73.5 CC-3-V1 7% Δn [589 nm, 20 ° C]: .1007 CCQU-3-F 12% Δε [1 kHz, 20 ° C]: +7.8 PUQU-2-F 9% γ ₁ [mPa.s, 20 ° C]: 57 PUQU-3-F 12% V ₁₀ [V]: 1.48 CCP-V-1 14% CCP 30CF3 8th % CCGU-3-F 3% CBC 33 1 %

8th% 100%

Mixture example 2

CCP 30CF3 4% Clearing point [° C]: 78.0 CCQU-3-F 12% Δn [589 nm, 20 ° C]: 0,102 CC-4-V 14% Δε [1 kHz, 20 ° C]: +9.7 CC-3-V1 14% γ ₁ [mPa.s, 20 ° C]: 72 PUQU-2-F 14% V ₁₀ [V]: 1.34 PUQU-3-F 13% CCP-V-1 20% CCGU-3-F 5%

4% 100%

Mixture example 3

CC-3-V1 17% Clearing point [° C]: 76.0 CC-3-V 31% Δn [589 nm, 20 ° C]: 0,102 PUQU-2-F 9% Δε [1 kHz, 20 ° C]: +5.5 PUQU-3-F 8th % γ ₁ [mPa.s, 20 ° C]: 52 BCH-32 4% V ₁₀ [V]: 1.86 CCP-V-1 14% CCGU-3-F 9%

8th% 100%

Mixture example 4

CC-3-V1 17% Clearing point [° C]: 76 CC-3-V 31% Δn [589 nm, 20 ° C]: 0.1023 PUQU-2-F 9% Δε [1 kHz, 20 ° C]: +5.5 PUQU-3-F 8th % γ ₁ [mPa.s, 20 ° C]: 52 BCH-32 4% V ₁₀ [V]: 1.86 CCP-V-1 14% CCGU-3-F 9%

8th% 100%

Mixture example 5

CC-3-V1 15% Clearing point [° C]: 75.5 CC-3-V 31% Δn [589 nm, 20 ° C]: .1066 PUQU-2-F 8th % Δε [1 kHz, 20 ° C]: +5.3 PUQU-3-F 8th % γ ₁ [mPa.s, 20 ° C]: 49 BCH-32 8th % V ₁₀ [V]: 1.90 CCP-V-1 11% CCGU-3-F 8th % PP 1-2V1 3%

8th% 100%

Mixture example 6

PUQU-2-F 7% Clearing point [° C]: 77.5 PUQU-3-F 10% Δn [589 nm, 20 ° C]: .1158 CC-3-V 36% Δε [1 kHz, 20 ° C]: +7.1 CCP-V-1 15% γ ₁ [mPa.s, 20 ° C]: 57 CCGU-3-F 8th% V ₁₀ [V]: 1.60 BCH-32 10% PGU-3-F 6%

8th% 100%

Mixture example 7

CC-3-V1 18% Clearing point [° C]: 75 CC-3-V 31% Δn [589 nm, 20 ° C]: .1082 PUQU-2-F 8th % Δε [1 kHz, 20 ° C]: +5.5 PUQU-3-F 11% γ ₁ [mPa.s, 20 ° C]: 50 BCH-32 10% V ₁₀ [V]: 1.82 CCP-V-1 6% CCGU-3-F 8th %

8th% 100%

Mixture example 8

PUQU-3-F 18% Clearing point [° C]: 75.5 CC-3-V 31% Δn [589 nm, 20 ° C]: .1090 CC-3-V1 10% Δε [1 kHz, 20 ° C]: +7.0 CCP-V-1 8th% γ ₁ [mPa.s, 20 ° C]: 57 CCGU-3-F 8th% V ₁₀ [V]: 1.65 BCH-32 10% PGU-3-F 7%

8th% 100%

Mixture example 9

PUQU-3-F 16% Clearing point [° C]: 75.5 CC-3-V 43% Δn [589 nm, 20 ° C]: .1226 CCGU-3-F 7% Δε [1 kHz, 20 ° C]: +7.1 BCH-32 6% γ ₁ [mPa.s, 20 ° C]: 56 APUQU-3-F 6% V ₁₀ [V]: 1.66 PGP-2-4 7% PGP-2-3 4% CBC 33 3%

8th% 100%

Mixture example 10

PUQU-3-F 16% Clearing point [° C]: 74.5 CC-3-V 43.5% Δn [589 nm, 20 ° C]: .1201 CCGU-3-F 9% Δε [1 kHz, 20 ° C]: +7.1 BCH-32 5.5% γ ₁ [mPa.s, 20 ° C]: 57 APUQU-3-F 6% V ₁₀ [V]: 1.64 PGP-2-4 5% PGP-2-3 4% CBC 33 3%

8th% 100%

Mixing Example 11

PUQU-3-F 10% Clearing point [° C]: 75 CC-3-V 43% Δn [589 nm, 20 ° C]: 0.1084 CC-3-V1 13% Δε [1 kHz, 20 ° C]: +5.3 CCGU-3-F 7% γ ₁ [mPa.s, 20 ° C]: 48 APUQU-3-F 6% V ₁₀ [V]: 1.88 PGP-2-4 6% PGP-2-3 4% CBC 33 3%

8th% 100%

Mixture example 12

CC-3-V 40% Clearing point [° C]: 74.5 CC-3-V1 11% Δn [589 nm, 20 ° C]: .1187 PUQU-3-F 3% Δε [1 kHz, 20 ° C]: +4.6 PGU-2-F 7% γ ₁ [mPa.s, 20 ° C]: 49 PGU-3-F 10% V ₁₀ [V]: 1.94 PGP-2-3 5% PGP-2-4 03.05% CCP 30CF3 2% CCP-V-1 06.05% CCGU-3-F 3% CBC 33 3%

6% 100%

Mixture example 13

PUQU-3-F 17% Clearing point [° C]: 76 CC-3-V 37% Δn [589 nm, 20 ° C]: .1193 CC-3-V1 5% Δε [1 kHz, 20 ° C]: +7.3 CCP-V-1 6% γ ₁ [mPa.s, 20 ° C]: 56 CCGU-3-F 8th% V ₁₀ [V]: 1.64 BCH-32 10% PGU-3-F 5% PPGU-4-F 3% PGP-2-3 3%

6% 100%

Mixture example 14

CC-3-V1 15% Clearing point [° C]: 76 CC-3-V 36% Δn [589 nm, 20 ° C]: .1092 PUQU-3-F 16% Δε [1 kHz, 20 ° C]: +5.6 BCH-32 10% γ ₁ [mPa.s, 20 ° C]: 51 CCP-V-1 4% V ₁₀ [V]: 1.87 CCGU-3-F 7% PPGU-4-F 3% PGP-2-4 3%

6% 100%

Mixing Example 15

PUQU-3-F 17% Clearing point [° C]: 75 CC-3-V 38% Δn [589 nm, 20 ° C]: .1184 CCP-V-1 9% Δε [1 kHz, 20 ° C]: +7.0 CCGU-3-F 10% γ ₁ [mPa.s, 20 ° C]: 58 BCH-32 10% V ₁₀ [V]: 1.65 PGU-3-F 6% PGP-2-4 4%

6% 100%

Mixture example 16

PGU-2-F 5% Clearing point [° C]: 75.0 CDU-2-F 6% Δn [589 nm, 20 ° C]: 0.0972 CCZU-3-F 15% Δε [1 kHz, 20 ° C]: +8.5 CC-3-V1 13% γ ₁ [mPa.s, 20 ° C]: 61 CC-3-V 21% k ₁ [pN, 20 ° C] 13.1 CCP-V-1 6% k ₃ / k ₁ [pN, 20 ° C] 0.95 CCP 30CF3 8th% V ₀ [V, 20 ° C] 1.30 CCP 40CF3 6% PUQU-2-F 7% PUQU-3-F 7%

6% 100%

Mixture example 17

PGU-2-F 06.05% Clearing point [° C]: 75.5 CDU-2-F 04.05% Δn [589 nm, 20 ° C]: 0.0976 CCZU-3-F 12% Δε [1 kHz, 20 ° C]: +8.4 CC-3-V1 13% γ ₁ [mPa.s, 20 ° C]: 61 CC-3-V 21% k ₁ [pN, 20 ° C] 12.6 CCP-V-1 8th% k ₃ / k ₁ [pN, 20 ° C] 1.02 CCP 30CF3 8th% V ₀ [V, 20 ° C] 1.29 CCP 40CF3 8th % PUQU-2-F 7% PUQU-3-F 6%

6% 100%

Mixture example 18

CC-3-V 19% Clearing point [° C]: 75.5 CC-3-V1 13% Δn [589 nm, 20 ° C]: 0.0975 CCP 30CF3 8th % Δε [1 kHz, 20 ° C]: +8.6 CCP 40CF3 8th % γ ₁ [mPa.s, 20 ° C]: 65 CCP-V-1 8th% k ₁ [pN, 20 ° C] 12.5 CCZU-3-F 13% k ₃ / k ₁ [pN, 20 ° C] 1.01 CDU-2-F 06.05% V ₀ [V, 20 ° C] 1.27 PGU-2-F 5.5% PUQU-2-F 7% PUQU-3-F 6%

6% 100%

Mixture example 19

CC-3-V 13% Clearing point [° C]: 78.5 CC-3-V1 12% Δn [589 nm, 20 ° C]: 0.1105 CCGU-3-F 5% Δε [1 kHz, 20 ° C]: +11.4 CCP 30CF3 8th % γ ₁ [mPa.s, 20 ° C]: 78 CCP-V-1 10.05% k ₁ [pN, 20 ° C] 13.0 CCZU-3-F 12% k ₃ / k ₁ [pN, 20 ° C] 0.98 CDU-2-F 9% V ₀ [V, 20 ° C] 1.12 PGU-2-F 07.05% PUQU-2-F 08.05% PUQU-3-F 08.05%

6% 100%

Mixing example 20

CC-3-V 05.14% Clearing point [° C]: 79.0 CC-3-V1 12% Δn [589 nm, 20 ° C]: .1097 CCGU-3-F 7% Δε [1 kHz, 20 ° C]: +11.3 CCP 30CF3 7% γ ₁ [mPa.s, 20 ° C]: 78 CCP-V-1 05.12% k ₁ [pN, 20 ° C] 12.4 CCZU-3-F 9% k ₃ / k ₁ [pN, 20 ° C] 1.06 CDU-2-F 7% V ₀ [V, 20 ° C] 1.10 PGU-2-F 8th% PUQU-2-F 08.05% PUQU-3-F 08.05%

6% 100%

Mixing example 21

CC-3-V 12.5% Clearing point [° C]: 79 CC-3-V1 12% Δn [589 nm, 20 ° C]: 0.1100 CCGU-3-F 7% Δε [1 kHz, 20 ° C]: +11.4 CCP 30CF3 8th % γ ₁ [mPa.s, 20 ° C]: 81 CCP-V-1 05.12% k ₁ [pN, 20 ° C] 12.2 CCZU-3-F 9% k ₃ / k ₁ [pN, 20 ° C] 1.07 CDU-2-F 9% V ₀ [V, 20 ° C] 1.09 PGU-2-F 7% PUQU-2-F 08.05% PUQU-3-F 8.5%

6% 100%

Mixture example 22

APUQU-2-F 8th % Clearing point [° C]: 73.0 CC-3-V 25% Δn [589 nm, 20 ° C]: .1005 CC-3-V1 13% Δε [1 kHz, 20 ° C]: +8.6 CCP-V-1 10.05% γ ₁ [mPa.s, 20 ° C]: 59 CCP-V2-1 10% k ₁ [pN, 20 ° C] 12.8 CDU-2-F 10% k ₃ / k ₁ [pN, 20 ° C] 1.01 PUQU-2-F 08.05% V ₀ [V, 20 ° C] 1.28 PUQU-3-F 9%

6% 100%

Mixture Example 23

APUQU-2-F 8th % Clearing point [° C]: 74.5 CC-3-V 26% Δn [589 nm, 20 ° C]: 0.0996 CC-3-V1 12% Δε [1 kHz, 20 ° C]: +8.5 CCP-V-1 10.05% γ ₁ [mPa.s, 20 ° C]: 59 CCP-V2-1 12% k ₁ [pN, 20 ° C] 12.7 CDU-2-F 8th % k ₃ / k ₁ [pN, 20 ° C] 1.05 PGU-2-F 2% V ₀ [V, 20 ° C] 1.28 PUQU-2-F 7.5% PUQU-3-F 8th %

6% 100%

Mixture example 24

APUQU-2-F 8th% Clearing point [° C]: 73 CC-3-V 25% Δn [589 nm, 20 ° C]: 0.1000 CC-3-V1 12% Δε [1 kHz, 20 ° C]: +8.5 CCP-V-1 10.05% γ ₁ [mPa.s, 20 ° C]: 60 CCP-V2-1 12% k ₁ [pN, 20 ° C] 12.2 CDU-2-F 05.09% k ₃ / k ₁ [pN, 20 ° C] 1.07 PGU-2-F 01.05% V ₀ [V, 20 ° C] 1.25 PUQU-2-F 07.05% PUQU-3-F 8th %

6% 100%

Mixture Example 25

APUQU-2-F 9% Clearing point [° C]: 78 CC-3-V 16% Δn [589 nm, 20 ° C]: 0.1118 CC-3-V1 12% Δε [1 kHz, 20 ° C]: +11.1 CCP 30CF3 7% γ ₁ [mPa.s, 20 ° C]: 74 CCP-V-1 11% CCP-V2-1 10% CDU-2-F 5.5% PGU-2-F 5% PUQU-2-F 10% PUQU-3-F 10%

04.05% 100%

Mixing example 26

APUQU-2-F 9% Clearing point [° C]: 79.5 CC-3-V 05.15% Δn [589 nm, 20 ° C]: .1112 CC-3-V1 12% Δε [1 kHz, 20 ° C]: +11.1 CCP 30CF3 7.5% γ ₁ [mPa.s, 20 ° C]: 72 CCP-V-1 05.11% CCP-V2-1 11% CDU-2-F 03.05% PGU-2-F 5% PUQU-2-F 10% PUQU-3-F 10%

5% 100%

Mixing example 27

APUQU-2-F 9% Clearing point [° C]: 78.5 CC-3-V 05.14% Δn [589 nm, 20 ° C]: 0.1114 CC-3-V1 12% Δε [1 kHz, 20 ° C]: +11.2 CCP 30CF3 7.5% γ ₁ [mPa.s, 20 ° C]: 76 CCP-V-1 05.11% k ₁ [pN, 20 ° C] 12.7 CCP-V2-1 11% k ₃ / k ₁ [pN, 20 ° C] 1.08 CDU-2-F 5% V ₀ [V, 20 ° C] 1.12 PGU-2-F 04.05% PUQU-2-F 10% PUQU-3-F 10%

5% 100%

Mixture example 28

CC-3-V 21% Clearing point [° C]: 74 CC-3-V1 6% Δn [589 nm, 20 ° C]: .1192 CCQU-2-F 11% Δε [1 kHz, 20 ° C]: +11.2 PUQU-3-F 17% ε _∥ [1 kHz, 20 ° C]: +15.0 PGU-2-F 7% γ ₁ [mPa.s, 20 ° C]: 77 PGU-3-F 12% V ₁₀ [V]: 1.23 CCP-V-1 17% V ₉₀ [V]: 1.88 CCGU-3-F 3%

6% 100%

Mixture example 29

CC-3-V 24% Clearing point [° C]: 75.5 CCQU-2-F 6% Δn [589 nm, 20 ° C]: .1210 PUQU-3-F 17% Δε [1 kHz, 20 ° C]: +12.7 PGU-2-F 5% ε _∥ [1 kHz, 20 ° C]: +16.4 PGU-3-F 6% γ ₁ [mPa.s, 20 ° C]: 82 CCP 30CF3 8th% V ₁₀ [V]: 1.21 PGP-2-3 1% V ₉₀ [V]: 1.88 CCP-V-1 18% CCGU-3-F 3%

12% 100%

Mixture Example 30

CC-3-V 24% Clearing point [° C]: 77.5 CCQU-2-F 6% Δn [589 nm, 20 ° C]: .1209 PUQU-3-F 17 Δε [1 kHz, 20 ° C]: +12.2 PGU-2-F 5% ε _∥ [1 kHz, 20 ° C]: +15.9 PGU-3-F 6% γ ₁ [mPa.s, 20 ° C]: 78 CCP 30CF3 8th% V ₁₀ [V]: 1.25 PGP-2-3 2% V ₉₀ [V] 1.90 CCP-V-1 18% CCGU-3-F 4%

10% 100%

Mixture Example 31

PGU-2-F 4% Clearing point [° C]: 69 PUQU-2-F 8th% Δn [589 nm, 20 ° C]: .1091 GGP-3-CL 4% Δε [1 kHz, 20 ° C]: +4.1 CC-3-V 35.5% ε _∥ [1 kHz, 20 ° C]: +6.9 CC-3-V1 13% γ ₁ [mPa.s, 20 ° C]: 47 PP 1-2V1 9% k ₁ [pN, 20 ° C] 13.0 CCP-V-1 11% k ₃ / k ₁ [pN, 20 ° C] 1.06 CCP-V2-1 2.5% V ₀ [V, 20 ° C] 1.88 BCH-32 8th %

5% 100%

Mixture Example 32

CDU-2-F 2% Clearing point [° C]: 75.5 PGU-2-F 3% Δn [589 nm, 20 ° C]: 0.0996 PUQU-2-F 07.05% Δε [1 kHz, 20 ° C]: +8.7 PUQU-3-F 8th% ε _∥ [1 kHz, 20 ° C]: +12.1 CCP-V-1 11% γ ₁ [mPa.s, 20 ° C]: 59 CCP-V2-1 05.11% k ₁ [pN, 20 ° C] 12.4 CC-3-V1 05.12% k ₃ / k ₁ [pN, 20 ° C] 1.12 CC-3-V 30.05% V ₀ [V, 20 ° C] 1.25 APUQU-2-F 8th %

6% 100%

Mixture Example 33

CDU-2-F 04.05% Clearing point [° C]: 74 PGU-2-F 5% Δn [589 nm, 20 ° C]: 0.1000 PUQU-2-F 8% Δε [1 kHz, 20 ° C]: +8.6 PUQU-3-F 8th % ε _∥ [1 kHz, 20 ° C]: +12.1 CCP-V-1 11% γ ₁ [mPa.s, 20 ° C]: 60 CCP-V2-1 6% k ₁ [pN, 20 ° C] 12.1 CC-3-V1 12% k ₃ / k ₁ [pN, 20 ° C] 1.10 CC-3-V 31.05% V ₀ [V, 20 ° C] 1.25 APUQU-2-F 8th%

6% 100%

Mixing Example 34

CCP 30CF3 7% Clearing point [° C]: 80 PGU-2-F 5.5% Δn [589 nm, 20 ° C]: .1096 PUQU-2-F. 8.5% Δε [1 kHz, 20 ° C]: +10.9 PUQU-3-F 9% ε _∥ [1 kHz, 20 ° C]: +14.4 CC-3-V1 12% γ ₁ [mPa.s, 20 ° C]: 71 CC-3-V 05.21% k ₁ [pN, 20 ° C] 13.0 CCP-V-1 11.5% k ₃ / k ₁ [pN, 20 ° C] 1.08 CCP-V2-1 10% V ₀ [V, 20 ° C] 1.15 APUQU-2-F 08.05%

06.05% 100%

Mixture Example 35

PUQU-2-F 11% Clearing point [° C]: 75 PUQU-3-F 05.09% Δn [589 nm, 20 ° C]: 0.1001 CCP 30CF3 8% Δε [1 kHz, 20 ° C]: +13.9 CC-3-V 25% ε _∥ [1 kHz, 20 ° C]: +17.9 CC-3-V1 11% γ ₁ [mPa.s, 20 ° C]: 79 CCZU-3-F 01.05% k ₁ [pN, 20 ° C] 11.4 CCQU-3-F 10% k ₃ / k ₁ [20 ° C] 1.11 CCGU-3-F 10% V ₀ [V, 20 ° C] 0.96 APUQU-2-F 9%

5% 100%

Mixing example 36

PUQU-2-F 11% Clearing point [° C]: 75.5 PUQU-3-F 9.5% Δn [589 nm, 20 ° C]: 0.0996 CCZU-3-F 05.09% Δε [1 kHz, 20 ° C]: +13.4 CC-3-V 35% ε _∥ [1 kHz, 20 ° C]: +17.5 CCQU-3-F 10% γ ₁ [mPa.s, 20 ° C]: 80 CCGU-3-F 9% k ₁ [pN, 20 ° C] 11.0 APUQU-2-F 9% k ₃ / k ₁ [20 ° C] 1.07

7% V ₀ [V, 20 ° C] 0.95 100%

Claims (14)

1. Liquid-crystalline medium of positive dielectric anisotropy based on a mixture of compounds, characterised in that it comprises one or more compounds of the formula I

   

   in which

   R¹ denotes a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH₂ groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another,

   A denotes a ring system of the formulae

   

   

   

   pointing to the left or right,

   Z¹, Z² denote a single bond, -C≡C-, -CF=CF-, -CH=CH-, -CF₂O- or -CH₂CH₂-, where at least one group from Z¹ and Z² denotes the group -CF=CF-,

   X denotes F, Cl, CN, SF₅ or a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH₂ groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another,

   L¹, L², L³, L⁴, L⁵ and L⁶ each, independently of one another, denote H or F, and

   m denotes 0 or 1,

   and
   additionally one or more selected compounds of the general formulae K-1 to K-12:

   

   

   

   

   

   

   

   

   

   

   

   

   in which

   R⁰ denotes n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 C atoms.
2. Liquid-crystalline medium according to Claim 1, characterised in that

   X denotes F, Cl, CN, or a halogenated alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH₂ groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another.
3. Liquid-crystalline medium according to Claim 1 or 2, characterised in that

   m denotes 1.
4. Liquid-crystalline medium according to at least one of Claims 1 to 3, characterised in that it comprises one, two or more compounds of the formulae I-1 to I-30:

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   

   in which
   R¹ has the meaning indicated in Claim 1 and n stands for 1, 2, 3, 4, 5, 6, 7 or 8.
5. Liquid-crystalline medium according to at least one of Claims 1 to 4, characterised in that it additionally comprises one or more selected compounds of the general formulae Z-1 to Z-9:

   

   

   

   

   

   

   

   

   

   in which

   R^1a and R^2a each, independently of one another, denote H, CH₃, C₂H₅ or n-C₃H₇,

   R⁰ denotes n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 C atoms,

   alkyl, alkyl* denote an unsubstituted n-alkyl radical having 1 to 7 C atoms, and

   alkenyl denotes an unsubstituted alkenyl radical having 2-7 C atoms.
6. Liquid-crystalline medium according to at least one of Claims 1 to 5, characterised in that it additionally comprises one or more compounds selected from the group consisting of the general formulae II, III, IV, V and VI:

   

   

   

   

   

   in which

   R⁰ denotes n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 C atoms,

   X⁰ denotes F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkenyloxy or halogenated alkoxy having up to 6 C atoms,

   Z⁰ denotes -C₂F₄-, -CF=CF-, -C₂H₄-, -(CH₂)₄-, -OCH₂-, -CH₂O-, -CF₂O- or -OCF₂-,

   Y¹ to Y⁴ each, independently of one another, denote H or F,

   r denotes 0 or 1, and

   t denotes 0, 1 or 2.
7. Liquid-crystalline medium according to at least one of Claims 1 to 6, characterised in that it additionally comprises one or more compounds selected from the group consisting of the general formulae XIV and XV:

   

   

   in which

   R⁰ denotes n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 C atoms,

   X⁰ denotes F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkenyloxy or halogenated alkoxy having up to 6 C atoms,

   rings A and B, independently of one another, denote 1,4-phenylene which is substituted by 0, 1 or 2 fluorine, and

   where in each case at least one of the 1,4-phenylene rings is mono- or polysubstituted by fluorine atoms.
8. Liquid-crystalline medium according to at least one of Claims 1 to 7, characterised in that it additionally comprises one or more compounds of the formulae E-a to E-d:

   

   

   

   

   in which

   R⁰ has the meanings indicated in Claim 1.
9. Liquid-crystalline medium according to at least one of Claims 1 to 8, characterised in that it comprises one or more compounds of the formulae IIa to IIg:

   

   

   

   

   

   

   

   in which
   R⁰ has the meanings indicated in Claim 1.
10. Liquid-crystalline medium according to at least one of Claims 1 to 9, characterised in that it comprises one or more compounds of the formulae O1 and O2:

    

    

    in which
    alkyl and alkyl* each, independently of one another, denote a straight-chain or branched alkyl group having 1-7 carbon atoms.
11. Liquid-crystalline medium according to at least one of Claims 1 to 10, characterised in that it comprises one or more dioxane compounds of the formulae D1 and/or D2:

    

    

    in which

    R⁰ has the meanings indicated in Claim 3.
12. Use of the liquid-crystalline medium according to at least one of Claims 1 to 11 for electro-optical purposes.
13. Electro-optical liquid-crystal display containing a liquid-crystalline medium according to at least one of Claims 1 to 11.
14. Compounds of the formula Ic

    

    in which

    R¹, L¹, L², L³, L⁴, L⁵, L⁶ and X have the meaning indicated in Claim 1.